Jakarta , Indonesia -LRB- CNN -RRB- -- The Mount Merapi volcano in Indonesia erupted at least three times Tuesday , forcing thousands of nearby residents to flee .

Indonesian media reported that 15 people were killed , including some journalists who were staying in a guesthouse to get close to the volcano . CNN could not independently verify those reports .

Mount Merapi , which looms on the horizon north of the major city of Yogyakarta , is one of Indonesia 's most active volcanoes and lies in one of the world 's most densely populated areas . The volcano has a summit elevation of nearly 10,000 feet -LRB- 3,000 meters -RRB- .

Christian Awui , a rescuer at the scene , told CNN that the first thing that residents heard were sirens from an early warning system announcing the coming eruptions .

`` There was panic , '' he said . `` You could hear the rumbles of the volcano . ''

People ran to a refugee camp about 4 kilometers -LRB- 2.5 miles -RRB- away .

Because it was still dark , it was hard to tell how the eruptions compared with previous ones , Awui said .

Some nongovernmental relief agencies were poised to offer immediate help . One of them was World Vision Indonesia , a Christian relief and development agency .

`` Right now , our biggest concern is the children , '' said Fadli Usman , World Vision Indonesia 's rapid assessment team leader . `` Children are always forgotten in the early moments of a disaster like this . My first task will be to assess the needs of the children and their families in the evacuation centers so our team can begin to help them . ''

Usman said about 1,500 people -- mostly women and children -- had found refuge at a four-building shelter about 7 miles -LRB- 12 kilometers -RRB- from the volcano . The evacuees , he said , are worried about the men who stayed behind to guard their homes and fields on the mountain .

A dusting of ash covered motorbikes and cars at the shelter parking lot , the relief worker said . The heavy ash fallout also obscured any view of the mountain from his location , he said .

Usman had reported earlier that traffic was heavy as people left the region near the mountain . The traffic was not chaotic , he said , and the road was open and under control .

CNN 's Brian Walker contributed to this report .

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About 1,500 people were receiving aid at a shelter , a relief worker said

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Relief focus is on the children , a nongovernmental agency says

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Mount Merapi is one of Indonesia 's most active volcanoes

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It is in a densely populated area , near the city of Yogyakarta